Stuck with Proxy_Pass - help needed

Hello

I have setup a proxy pass to point a URL to an internal web server which uses a self signed certificate.

I have a DNS entry point my URL "wifi.example.com" to my nGINX server 172.28.6.131

I have setup a config entry in sites-avaliable so that when someone surfs to wifi.example.com it will redirect to https://172.28.8.249:8443

Problem is I get wifi.example.com sent an invalid response and ERR_SSL_PROTOCOL_ERROR

The config on NGINX is as follows

server {
listen 443;
server_name wifi.example;

location / {
proxy_pass https://172.28.8.249:8443;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_ssl_session_reuse off;
}
}

I can confirm the configuration is redirecting as I have other configurations pointing to other internal servers but only using HTTP and they are all working just fine. I seem to be stuck when it comes to HTTPS. The server it is redirecting is only a self signed certificate.

Can anyone assist?

Ross